The field of the present invention is composite ceramic filament/metal matrix members. More particularly, the present invention relates to rotor members for gas turbine engines having composite ceramic filament/metal matrix portions therein. Such a unitary rotor member includes an integral reinforcing portion defined by such a ceramic filament/metal matrix composite member. Still more particularly, the present invention relates to a method of making a ceramic filament/metal matrix composite hoop member. A method of making a unitary member including such a composite ceramic filament/metal matrix hoop reinforcing portion is also disclosed.
Conventional methods of making filament reinforced polymer matrix composite rings is disclosed in U.S. Pat. 3,966,523 to Jakobsen et al, issued 29 June 1976. The Jakobsen teaching provides a filament reinforced polymer matrix ring which is intended to remain a separate reinforcing component. Similar conventional teachings are set forth in U.S. Pat. Nos. 3,765,796 and 3,787,141 wherein rotor members for turbine engines are shown to include fiber reinforced composite reinforcing rings. These reinforcing rings are received within annular cavities of the turbine engine rotor member and receive centrifugally induced stresses upon relative radial growth of the metallic components of the rotor member. Although the reinforcing hoop members of composite material may be captured within the rotor member, they remain separate component parts which are subject to relative rotation and vibrational imbalances.
It is understood in the pertinent art that the high tensile strength provided by fiber reinforced composite materials may advantageously be employed to sustain centrifugally induced tangential stresses within a high speed rotor member. However, as is illustrated by the above-outlined conventional teachings, the fiber reinforced composite member has always been considered as a separate reinforcing component which must be supported and restrained within a rotor member of a turbine engine. Such a separate reinforcing component presents many problems with respect to its restraint and support prior to its assuming its full function as a reinforcing member. That is, the metallic components of the rotor member will experience much greater radial growth in response to centrifugally induced stresses than does the composite member. In order to best utilize such a composite reinforcing hoop, it is therefore required that the metallic components be allowed to sustain a considerable portion of the centrifugally induced stresses and to undergo such radial growth before additional centrifugally induced stresses are transferred to the composite reinforcing hoop member. Thus, prior to the time of assuming its full reinforcing function, the composite hoop member is somewhat free to assume non-concentric positions with respect to the rotational axis of the rotor member. Of course, should the composite reinforcing member deviate significantly from the rotational axis of the rotor member, very significant vibrational forces are sure to result.
An additional aspect of such conventional teachings is that only radially outwardly directed forces may be transferred to the composite member by contact between annular surfaces at the inner bore of the composite hoop member and annular surfaces at an inner wall of the metallic components of the rotor member. Consequently, the metallic components of the rotor member must be designed to sustain significant radially-directed tensile stresses in order to transfer the centrifugally induced tangential stresses to the inner wall portion of the metallic components. Of course, such a design inexorably results in the metallic components of the rotor member being heavier than desired.